Is the inverse problem technique appropriate for structural health assessment?

Structural health assessment techniques using system identification-based approaches have recently generated a considerable amount of multidisciplinary research interest. However, in 1979, it was stated that the inverse transformation technique could not identify a system with measured response information. Presence of many sources of error including noise, high frequency content, slope, DC bias, etc. in the measured response information were considered to be the major reasons. However, removing these sources from the measured responses may not be adequate to eliminate the non-convergence problem. In this article, it is conclusively demonstrated that a system can be identified if the amplitude and phase shift errors embedded in the measured responses are mitigated properly. The noise may not be the primary reason for the non-convergence. The conclusions made here are primarily based on the analytical and experimental works completed by the author and his team. Their experience indicates that the system identificationbased structural health assessment techniques have unlimited application potential.